U.S. health officials have embarked on one of the most comprehensive evaluations of child health ever undertaken in the United States. Researchers will be collecting data on a host of environmental and genetic factors that impact children's health and the health of the adults they will become. Doctors hope the results will shed new light on risk factors for autism, obesity and a host of other childhood health problems.

The Southwest Freeway is a major highway near the Voice of America and the U.S. Capitol. The freeway gets clogged when people are on their way to and from work. Just two blocks away is Amidon Elementary School. On a code red day the air is not healthy to breathe. Studies have shown that air pollution can cause lung problems in children: it makes asthma worse and has been linked to learning and memory problems.

Now another study is underway, the largest, most ambitious health study in U.S. history. It will look at how children react to environmental factors: the air they breathe, the water they drink, the soil they walk on and the food they eat. The study will also include other factors: family dynamics, genetics, television viewing habits and many other things.

"Our goal is to understand how you can get the healthiest, most robust child to develop into a healthy and contributing member of adult society," said Dr. Steven Hirshfeld, the study director.

The study aims to enroll 100,000 children all across America in cities and rural communities, collecting health data on them starting before birth and continuing until age 21. Jennifer is three months pregnant. She is participating at the University of California, Los Angeles, or UCLA, one of the seven study centers across the country.

"Living in Los Angeles I'm concerned about the pollution and the smog, and I'm also concerned about what I put in my body: is the food genetically modified, is the food organic? Do they [the manufacturers] add chemicals or preservatives, and how do those things have an effect on an unborn child?" Jennifer asked.

Doctors will study 4,000 children in the Los Angeles area that could answer Jennifer's questions. They will also enroll 1,000 children in a more rural area to see what impact pesticides used on nearby farms might be having on their health. Dr. Michael Lu is one of the lead investigators at UCLA.

"We're examining various child conditions such as asthma and autism, pre-term birth and birth defects, obesity and diabetes and various behavioral and learning problems," said Lu.

The goal is to create a data base that researchers the world over can use. Dr. Hirshfeld says he hopes the data will supplement knowledge researchers already have.

"We have knowledge gaps with many of the important factors that influence not only the health, well-being and development of children, but that begin the foundations of what could turn into chronic conditions for adults," said Hirshfeld.

The study will try to determine possible causes of birth defects. It will also study behavior, learning, and mental health disorders.

"I think this study has the potential to change the way we look at childhood health and development," added Lu.

It may also change laws concerning child health and the environment. The findings will be available as research progresses. That way officials can develop prevention strategies and health and safety guidelines so children can live healthier lives and grow into healthier adults.